Buse M G
Horm Metab Res. 1981 Sep;13(9):502-5. doi: 10.1055/s-2007-1019316.
Rats (80-100 g) were fasted for 48 hours prior to receiving i.v. infusions of [(14)C]tyrosine (0.5 ml/hour)in 0.9% saline or 2.8 M glucose or 2.5 M glucose with 0.1 M each of leucine, isoleucine and valine. The incorporation of [(14)C]tyrosine into proteins of different muscles was measured at the end of six hour infusions. Heart, soleus and diaphragm muscles incorporated more tyrosine into proteins than psoas and gastrocnemius under all conditions. Infusions of glucose alone did not accelerate tyrosine incorporation significantly in the muscles tested. The addition of branched chain amino acids to glucose markedly increased tyrosine incorporation into proteins in the diaphragm, and to a lesser extent in soleus and psoas. No effect was detectable in heart and gastrocnemius. Previous reports of differences in protein synthetic rates between different types of muscles are confirmed. Additionally, the data suggest that branched chain amino acids may be rate limiting for muscle protein synthesis in fasted rats in vivo, and that the responsiveness to branched chain amino acids differs between muscles.
体重80 - 100克的大鼠在静脉输注含[(14)C]酪氨酸（0.5毫升/小时）的0.9%生理盐水、2.8 M葡萄糖或含0.1 M亮氨酸、异亮氨酸和缬氨酸的2.5 M葡萄糖之前禁食48小时。在输注6小时结束时，测定[(14)C]酪氨酸掺入不同肌肉蛋白质中的情况。在所有条件下，心脏、比目鱼肌和膈肌比腰大肌和腓肠肌将更多的酪氨酸掺入蛋白质中。单独输注葡萄糖并未显著加速受试肌肉中酪氨酸的掺入。在葡萄糖中添加支链氨基酸显著增加了膈肌中酪氨酸掺入蛋白质的量，比目鱼肌和腰大肌中增加的程度较小。在心脏和腓肠肌中未检测到影响。先前关于不同类型肌肉之间蛋白质合成速率差异的报道得到了证实。此外，数据表明支链氨基酸可能是禁食大鼠体内肌肉蛋白质合成的限速因素，并且不同肌肉对支链氨基酸的反应性不同。
